Among the boxes to be ticked when designing a major project, the Holland Board of Public Works always includes sustainability.
The BPW’s latest project is being recognized for its forward-thinking sustainability efforts. The public utility’s new anaerobic digester earned an ENVISION Gold rating for sustainability this month.
The Institute for Sustainable Infrastructure
’s ENVISION is a third-party verification that major projects have considered environmental, social and economic impacts of civil infrastructure. The ENVISION framework dives deep into the planning, construction, and life cycle of a project, ensuring that major infrastructure is sustainable and resilient and maximizes benefits to the community.
“ENVISION goes beyond the basic efforts of project management and development into areas that benefit the community in a holistic way,” says Holland BPW General Manager Dave Koster. “Our goal is to bring as much value to those impacted by the project as possible.”
This is the utility’s second ENVISION rating. The Holland Energy Park was the first base-load power-generating plant to receive an ENVISON rating when it received a platinum rating from the organization in 2016.
The BPW’s anaerobic digester is a 105-foot-tall sphere located at the Holland Area Wastewater Reclamation Facility on River Avenue near the city’s downtown. When the anaerobic digester begins operation in the fall, it will both reduce and treat waste from the wastewater reclamation facility while also creating some of the energy needed to run the plant.
“Options for disposing of biosolids are increasingly difficult to find, and the costs are rising. Anaerobic digestion allows us to address these challenges in a sustainable way,” says BPW Operations Manager Joel Davenport.
The BPW’s budget to dispose of solid waste from the water treatment plant has gone from $700,000 to $2 million.
Anaerobic digestion will help alleviate that cost. The anaerobic digester is expected to reduce the amount of wastewater solids from the water reclamation process by approximately 50%, doing the same for disposal costs. The process breaks down the volatile part of the solids, which makes the waste more suitable for agriculture purposes and removes more of the liquid, which makes it easier to dispose of in a landfill.
The project is primarily being funded through a low-interest loan from the state’s Clean Water State Revolving Fund. The project also qualified for 20% principal forgiveness through the program’s Green Project Reserve, which provides principal forgiveness for projects that address green infrastructure, water and energy efficiency, or other environmentally innovative activities.
“In the case of the digester project, this represents $6 million in savings,” Davenport says. “This certainly helps with the financial sustainability of the project.”
“The anaerobic digester is another critical part of keeping our footprint small, reducing the amount of solid waste that we produce and increasing the quality of the solid waste leaving our facility,” the BPW’s annual report states. “As a sort of mechanical gut, the anaerobic digester utilizes bacteria who break down biosolids while producing biogases.”
This will allow the end waste product to be used for more applications, such as fertilizer for crops fit for human consumption or commercial lawn treatment.
Methane biogas is a byproduct of the anaerobic digestion process. Since the digester is an enclosed facility, the gas can be captured and used to heat and power the facility, itself. About half of the site’s energy will be generated by the anaerobic digestion process.
The process and enclosed facility mean smells are also reduced.
The 105-foot-tall sphere is noticeable along River Avenue. With something that big, builders can either choose to make it really stand out or to blend into its background. Given the digester’s proximity to downtown Holland, the BPW chose the later, Davenport says. The 105-foot-tall sphere was recently painted a blue-gray that blends into the sky behind — a paint color, the BPW calls “Macatawa Mist.”